Device for processing a three dimensional structure into a substrate

ABSTRACT

A device and method for processing a substrate, wherein a flexible force absorbing means is provide in at least a part of a tool plan and/or a reaction plan, so as to locally absorbing the forces applied by the planes. The flexible force absorbing mean having spring-like properties such that it is adapted to be elastically deformed when the tool plan and the reaction plan are pressed against each other.

FIELD OF THE INVENTION

This invention relates generally to a device and a process for processing a substrate, e.g. forming a three-dimensional structure, nanostructure, hologram or similar relief diffraction pattern into a substrate by use of a re-configurable mould.

BACKGROUND OF THE INVENTION

Various techniques for cutting and forming a substrate exist. Cutting is done in different ways e.g. punching. Normally the cutting machine is provided with co-operating edges used to cut the material. Especially when cutting fine geometry's where allowable variations in the tolerances are relatively small, the tool with the cutting edges need to be renewed or renovated often, due to tear and ware of the tool. This makes the process relatively expensive.

Various casting techniques for forming microstructure surfaces exist. Typically a mould holds a liquid resin on the substrate during curing of the resin whereby the resin forms the microstructure. The mould may be provided with a rotating drum having a three-dimensional relief pattern forming the microstructure, or the mould may be provided with a planar plate having a relief pattern attached to one side. In order to create visible distortion in the diffraction pattern, the tolerances must be low and accordingly, the cost for making a mould is relatively high. The moulds have to be replaced after a number of moulding cycles, as the moulds are incorporated e.g. in rotational drums for mass replication of holograms, the costs for replacing moulds being high.

Only very small displacements of the mould in relation to the substrate during the casting will reduce the quality of the cast. Accordingly, existing systems for casting microstructures use highly rigid moulds and rigid devices for the casting process. The rigidity enables control over the casting process e.g. by reducing the risk of unwanted vibrations in the moulds.

When casting structures in liquid resins, the rigidity of the casting devices and moulds have almost no negative effect and therefore the makers of casting machines seems to strive towards more rigidity.

However, when casting in non-liquid materials such as directly in steel plates or similar ‘hard’ substrates, the rigidity disables the machine to take up tolerances occurring in the substrate. As an example, a metal plate will usually have a non-planar surface. When subjected to a completely rigid mould in a completely rigid machine, the deviations of the non-planar surface may easily be visually detectable in the structure. As an example, the non-planarity of the plate may be replicated in a non-even embossing depth, which gives visually detectable uneven reflection from the surface of the structure.

DESCRIPTION OF THE INVENTION

It is a primary object of the present invention to provide a technique and a device for processing, such as cutting or casting or embossing, structures into a substrate, e.g. into non-liquid materials or even into hard materials, and which overcomes the above mentioned problems.

Accordingly, the present invention relates to a device for processing a substrate; said device having a tool plan and a reaction plan, the tool plan comprising a multiple layer construction with:

-   -   a core having a substantially inflexible outer surface, and     -   at least one tool being attached to the surface of the core,         wherein flexible force absorbing means is provided in at least a         part of the tool plan and/or the reaction plan, so as to locally         absorb the forces applied by the planes.

The flexible force absorbing means is adapted to equalise the pressure along the core and/tool, so that possible sporadic unevenness along the length of the core and/or tool do not result in a higher local pressure in the area of the unevenness, as the force absorbing means will absorb/equalise such high pressure.

In some embodiments the flexible force absorbing means may be resilient. Thus the flexible force absorbing means may return to an initial position when pressure applied from the tool plan and/or the reaction plan is removed. In some embodiments the flexible force absorbing means may be chosen such that it is only elastically deformed when pressure is applied to said means. A reversible process may take place when the flexible force absorbing means performs the following steps; uncompressed state (prior to application of pressure from the tools)—compressed state (during application of pressure from the tools) —uncompressed state (subsequent to application of pressure from the tools). As the flexible force absorbing means may be only elastically deformed the thickness of the means may be the same before and after application of pressure. When the flexible force absorbing means is resilient the means may have spring like properties. An advantage of the resilient absorbing means may be that said means may be re-used contrary to non-flexible absorbing means which may be plastically deformed and thus must be replaced by a non-plastically-deformeed piece prior to further use of the device.

The present invention may relate to a device for processing a substrate, said device having a tool plan and a reaction plan, the tool plan comprising a multiple layer construction with:

-   -   a core having a substantially inflexible outer surface, and     -   at least one tool being attached to the surface of the core,         wherein flexible force absorbing means is provided in at least a         part of the toot plan and/or the reaction plan, the flexible         force absorbing means being adapted to be elastically         deformable, so as to locally absorb the forces applied by the         planes to a substrate.

The flexible force absorbing means may be adapted to be elastically deformable at room temperature and/or at atmospheric pressure. In some embodiments room temperature may be between 0 degrees Celsius and 100 degrees Celsius. In some embodiments it may be essential the of the temperature of the air/space surrounding the device is such that a worker may operate the machine without encapsulating the machine or without dressing the worker in clothing protecting him from extreme temperatures. Analogously it may be essential that the pressure is such that a worker may operate the machine without encapsulating the machine and/or the worker. Thus atmospheric pressure may, in this application, be seen to be pressures in which a human being can survive for a longer or shorter period of time. The tool plan and/or the reaction plan may be heated during operation. A substrate being processed may be heated so as to soften the substrate.

In some embodiments it may be essential to avoid any encapsulation of the device which reduces the operation speed e.g. resulting from complicated handling of a work pieces. Naturally in some countries there may be legal requirements regarding encapsulation of the device which may be followed. The operation speed may be 0-10.000 meters of substrate per hour such as 2.000-8.000 meters per hour, such as 4.000-5.000 meters per hour. The work pieces/substrates may be plates of material e.g. plastic or metal, being 1 meter long. The pieces/substrates may be coils.

The movements of the tool plan and the reaction plan may be synchronised vertically and/or horizontally. If the two plans are provided as a stamping process means for moving a work piece through the stamping process may be synchronised with the stamping process. If the two planes are provided as one or more drums for rotative processing of the first layer said drums may be synchronised.

In an embodiment a tool may comprise a tool plan and a reaction plan provided with co-operating edges for cutting a substrate. The tool may be used for cutting such as die cutting or punching e.g. in an eccentric press, but could also be used in a rotative drum adapted to cut substrate with co-operating edges. Said drum may be adapted to cut and/or shape e.g. emboss a microstructure into a substrate.

The tool may also be used for micro embossing, macro embossing, marking up cutting-lines on a sheet/plate.

Another embodiment comprises a tool having a tool plan and a reaction plan wherein at least one of either the tool plan or the reaction plan may be adapted to shape at least a first layer of the substrate into a predefined form. Such tool may be used in a hydraulic press for shaping a substrate, but could also be used in a rolling process.

The tool plan could be a hard plan surface corresponding to the known tool plans of regular stamping machines. The stamp could be moved up and down by a rigid cam disc, linear actuators or the like. The stamp should provide a sufficient pressure against the substrate and the reaction plan to emboss the structure into the substrate. The tool plan or the reaction plan could both be provided with rigidity since the flexible force absorbing means of the tool plan or the reaction plan or both the tool plan and the reaction plan, will take up tolerances.

Preferably, the flexible force absorbing means are provided so that the flexibility may be changed. According to an embodiment of the invention, the flexible force absorbing means are provided in the form of a resilient adhesive tape attached to the surface of the tool plan and/or to the surface of the reaction plan forming a force absorbing layer of the device. The resiliency and thus the capability of the device to take up tolerances may easily be changed e.g. by changing the type of adhesive tape or the thickness of the adhesive tape.

The flexible force absorbing means may comprise at least one force absorbing layer provided in the multiple layer construction and/or being attached to the reaction plan.

Both the tool plan and the reaction plan may be provided with a force absorbing layer.

Preferably, the flexible force absorbing layer is provided in the multiple layer construction between the core and the tool. This embodiment is advantageous, as the absorbing layer then absorbs all sporadic unevenness along the entire length of the core and/or tool.

The flexible force absorbing means may, according to another embodiment, be provided as a hard plan e.g. of metal being attached to the surface of the tool plan and/or the reaction plan and provided with bouncing springs facing the tool plan and/or the reaction plan. The springs may either be provided with an adjustable characteristics or be detachably mounted for replacement with springs having a characteristic matching the individual embossing tasks and substrate materials.

According to a preferred embodiment of the invention, the tool plan is a cylindrically shaped drum for rotative embossing of the tree dimensional structure and the reaction plan is likewise a cylindrical drum or nip roll for providing the necessary counter pressure.

The device may be adapted for embossing the structure into a non-planar hard substrate having a planar deviation or roughness δ by:

-   -   selecting a thickness τ of the force absorbing layer so that the         thickness extends the planar deviation δ.

In that way the force absorbing layer will be capable of taking up at least a substantial part of the deviation by compression of the layer. It will further be preferred that the material for the force absorbing layer is selected so that the force required to compress the material should be less than the force required for embossing the structure into the substrate, i.e. the non-compressed flexible layer should be softer than the surface of the substrate.

Preferably, the force absorbing layer is selected with a thickness in the range of 0.1-5 mm, such as 0.2-4.5 mm, such as 0.3-4.0 mm such as 0.4-3.5 mm, such as 0.5-3 mm, such as 0.6-2.5 mm, such as 0.7-2.0 mm, such as in the size of 1.5 mm.

Preferably the absorbing layer is selected with an elasticity enabling the layer to provide a force to the hard substrate, which force extends the yield point of the hard substrate at a given rate of compression γ, and wherein the thickness of the flexible force absorbing layer at that rate of compression γ extends the planar deviation δ.

The force absorbing layer could be provided in the form of a double sided adhesive tape for attaching at least one tool, such as a shim, to the outer surface of the core, e.g. selected with a thickness in the range of 0.1-0.5 mm, such as in the range of 0.20-0.4 mm, such as in the range of 0.21-0.3 mm, such as in the range of 0.22-0.26 mm, such as 0.24 mm.

The core may be provided with a steel surface, so that it is easy to provide an adhesive tape having the necessary attachment strength. As an example, the double sided adhesive tape 3M-type 9586 F gives a sufficient adhesion to steel. Moreover, it will be easy to provide an embossing or reaction surface with sufficient rigidity from steel. For ensuring the best adhesion, a roughness in the range of 1-100 microns of the steel surface will be preferred. Thereby it will be possible to provide an adhesion to steel in the range of 6-12 N/cm, such as in the range of 7-11 N/cm, such as in the range of 8-10 N/cm, such as 9 N/cm.

Preferably, one or both sides of the double sided adhesive tape are provided with an acrylic based adhesive and preferably the tape is provided with a dynamic share in the range of 50-100 N/cm², e.g. in the size of 70 N/cm².

The adhesive layer of the tape may be provided with a permanent adhesion so that it will be possible to reuse the tape and to refit the shims to the flexible layer, which will make refitting easier and faster. Thus, the invention provides a much more flexible device, as the tool can be changed very easy.

The processing may comprise embossing of a three-dimensional structure into the substrate, such as a nano-structure into the substrate, or it may comprise embossing of a nano-structure into a metallic substrate.

According to a second aspect, the invention relates to a drum for rotative processing of a first layer of a multiple layer substrate, the first layer having a first degree of hardness and the succeeding layers having a second degree of hardness, said drum having:

-   -   a core with a substantially inflexible outer surface,     -   a flexible force absorbing layer with a third degree of         hardness, the flexible force absorbing layer being peripherally         attached to the core, and     -   a matrix having the three dimensional structure, the matrix         being peripherally attached to the flexible force absorbing         layer,         wherein the flexible force absorbing layer is selected so that         the third degree of hardness is higher than the first degree of         hardness and lower than the second degree of hardness so as to         ensure that the three dimensional structure is processed into         the first layer but not into subsequent layers.

According to a third aspect, the present invention relates to a method for processing a three dimensional structure into a first layer of a substrate by use of a device having a tool plan and a reaction plan, the tool plan comprising a multiple layer construction, said method comprising the steps of:

-   -   providing a tool being attached to the surface of a core of the         tool plan, the core of the tool plan being provided with a         flexible force absorbing layer, and     -   disposing a sheet of the substrate between the tool plan and the         reaction plan, and     -   applying pressure so as to process the substrate.

According to a fourth aspect, the present invention relates to a method for attaching a tool to the surface of an tool plan of a device for processing a substrate, said method comprising providing a resilient layer between the tool plan and the tool, the resiliency of the layer being selected so that a non-compressed layer is softer than the surface of the substrate. The tool may be a shim or any other kind of tool.

The substrate mentioned in connection with any of the above-mentioned aspects may be selected from the group consisting of lacquers, carton, cardboard, polymers, printing inks, plastics, metal such as tin, aluminium, copper, lead, steel. The Brinell-hardness (Hs 10) of the substrate may range from 10 N/mm² to 1000 N/mm².

The present invention provides a technique for processing a substrate at high speeds, (such as 1-2 meter sheet material plade per hour) and at room-temperature. In particular, the technique should be applicable for high-speed production lines for manufacturing e.g. food containers.

Of course the pressure applied to the substrate should be so high that the wanted shape is embossed or punched or cut in the substrate. Preferably, the pressure is within the range of 100-1000 kg/cm². The combination of pressure and type of substrate will be chosen so as to obtain the best result of the processing.

Due to this device, it is possible to control a processing of a substrate held by a bearing material in an easy way, and where a deformation of the bearing material (or core material) is avoided due to the use of the flexible force absorbing layer, e.g. the double sided adhesive tape.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the invention will now be described in details with reference to the drawing in which:

FIG. 1 shows an embossing drum according to the present invention,

FIG. 2 shows a side view of the drum shown in FIG. 1,

FIG. 3 shows an alternative embodiment of a device with an upper pressing member in the form of an embossing stamp,

FIG. 4, 5 and 6 show diagrams of the principles of the flexible attachment of shims to an embossing device, and

FIG. 7 shows a machine for embossing a three dimensional structure into a substrate.

The embodiment hereinafter is with respect to embossing of holograms into hard surfaces e.g. of steel plates. Referring to FIG. 1, a device according to the invention comprises an embossing roll 3 and a nip roll 7. The nip roll provides the necessary counter pressure—the surface of the nip roller corresponds to the reaction plan. The embossing roll is provided with a number of shims 1 attached to the roll by a resilient adhesive tape 2. The embossing roll and the nip roll is carried by bearings 4, 6. One of the rolls (in FIG. 1, the embossing roll 3) is provided with means for adjusting the pressure between the embossing roll and the nip roll by adjusting the gab between the rolls. The absorbing layer in the bearing absorbs the pressure. The absorbing layer 5 may be distorted by predetermined “retaining force” in order to control the upwards movement of the embossing roll 3 when introducing a sheet material (or any other material to be processed) between the rolls 3, 7.

As an example the embossing roll may be held by a servo driven guide rail enabling the roll to be shifted linearly. One or both of the embossing roll and/or the nip roll is rotated by power driven means. As an example, the rolls are rotated in a synchronised fashion wherein the peripheral speed of the rolls are adjusted to the speed of previous and/or succeeding rolls or sets of rolls in a process machine for printing and embossing substrates from a coil. In order to avoid slipping of the plates between the embossing roll and the nip roll, both of the rolls may preferably be driven by synchronised powered means so that the peripheral speed of the rolls is the same. Preferably, the diameter of the rolls is the same. Regular lacquer machine or printing machines which provides a setup of rolls and nip rolls according to the above description exits on the market. However, none of these machines are provided with shims attached to the rolls as described above.

As shown in FIG. 1, a plurality of shims may be attached to the surface of one single embossing roll. In that way the use of the surface area of the roll may be optimised and many replicas may be embossed for each round of the embossing roll. The shims attached to one roll (or tool plan) may be identical or they may be different.

As seen in FIG. 2, the resilient adhesive tape 2 is compressed during the embossing of the hologram into the substrate. The wedge 9 serves for attaching a wrapping sheet to the surface of the roll. In this way it is even faster to change the replica to be embossed by simply removing one wrapping sheet holding a number of shims attached to the sheet by resilient adhesive tape. According to a preferred embodiment, the wrapping holding a number of shims may be provided with sufficient resiliency to provide the flexibility. Thereby the shims may be attached directly to the wrapping sheet and thereby a number of sheets may be replaced simultaneously by replacing the wrapping sheet.

FIG. 3 shows an embodiment of the device wherein the drum is replaced with a stamp capable of moving along a vertical axis towards a table 8. The stamp is provided with at least one shim 1 being attached to the stamp by a resilient adhesive tape 2.

FIG. 4, 5 and 6 show the principles of embossing according to the present invention. FIG. 4 shows the principles of applying a force from a movable plan, e.g. a drum or stamp through a flexible material, e.g. a resilient adhesive tape, foam rubber or similar resilient means to a tool (shim) for embossing a three dimensional structure into a substrate. The reaction plan serves for providing the necessary counter pressure against the stamp or drum. In FIG. 5, Δf expresses the force increase resulting from the compression of the resilient tape or similar flexible means. The flexible layer will absorb non-planarity and tolerances of the surface of the substrate. Δh expresses the permanent deformation of the substrate.

FIG. 7 shows a machine for embossing, the machine comprising a first storage 17 for storing steel plates 14 prior to the embossing, a set of embossing drums 13,16 (a movable plan and a reaction plan) and a second storage 11 for storing the steel plates after the embossing. The steel plates are transported on means 15. The pressure may be adjusted by the adjusting means 12. 

1. A device for processing a non-planar hard substrate having a planar deviation δ, said device having a tool plan and a reaction plan, the tool plan comprising a multiple layer construction with: a core having a substantially inflexible outer surface, and at least one tool being attached to the surface of the core, and wherein flexible force absorbing means is provided in at least a part of the tool plan and/or the reaction plan and comprises at least one force absorbing layer provided in the multiple 10 layer construction, said layer having a thickness τ that exceeds said planar deviation δ.
 2. A device according to claim 1, wherein the flexible force absorbing means is resilient.
 3. A device according to claim 1, wherein the least one force absorbing layer is attached to the reaction plan.
 4. A device according to claim 1, wherein both the tool plan and the reaction plan are provided with a force absorbing layer.
 5. A device according to claim 1, wherein the flexible force absorbing layer is provided In the multiple layer construction between the core and the tool.
 6. A device according to claim 1, wherein the tool plan and the reaction plan are provided with co-operating edges for cutting the substrate.
 7. A device according to claim 1, wherein at least one of either the tool plan or the reaction plan are adapted to shape at least a first layer of the substrate into a predefined form.
 8. A device according to claim 1, wherein the tool plan is provided as a stamp for processing at least a first layer of the substrate by stamping.
 9. A device according to claim 1, wherein the tool plan is provided as a drum for rotative processing of at least a first layer of the substrate.
 10. A device according to claim 1, wherein the force absorbing layer is selected with a thickness in the range of 0.1-5 mm, such as 0.2-4.5 mm, such as 0.3-4.0 mm such as 0.4-3.5 mm, such as 0.5-3 mm, such as 0.6-2.5 mm, such as 0.7-2.0 mm, such as 1.5 mm.
 11. A device according to claim 1, wherein the flexible force absorbing layer is selected 40 with an elasticity enabling the flexible force absorbing layer to provide a force to the substrate, which force exceeds the yield point of the substrate at a given rate of compression γ, and wherein the thickness of the flexible force absorbing layer at that rate of compression γ exceeds the planar deviation δ.
 12. A device according to claim 1, wherein the flexible force absorbing layer is a double sided adhesive tape for attaching the at least one tool to the outer surface of the core.
 13. A device according to claim 12, wherein the double sided adhesive tape is selected with a thickness in the range of 0.1-0.5 mm, such as in the range of 0.20-0.4 mm, such as in the range of 0.21-0.3 mm, such as in the range of 0.22-0.26 mm, such as 0.24 mm.
 14. A device according to claim 1, wherein the core is provided with a steel surface.
 15. A device according to claim 14, wherein the steel surface is provided with a roughness in the range of 1-100 microns,
 16. A device according to claim 12, wherein the tape is provided with an adhesion to steel in the range of 6-12 N/cm, such as in the range of 7-11 N/cm, such as in the range of 8-10 (M/cm, such as 9 N/cm.
 17. A device according to claim 12, wherein the tape is attached to the core by an acrylic based adhesive.
 18. A device according to claim 12, wherein the tool is attached to the tape by an acrylic based adhesive.
 19. A device according to claims 12, wherein the adhesive layer of the tape is provided with a permanent adhesion so as to enable refitting of tool to the flexible layer.
 20. A device according to claim 19, wherein the tool comprises one or more shims to be adhered to the adhesive layer.
 21. A device according to claim 1, wherein the processing comprises embossing of a three dimensional structure into the substrate.
 22. A device according to claim 1, wherein the processing comprises embossing of a nano-structure into the substrate.
 23. A device according to claim 1, wherein the processing comprises embossing of a nano-structure Into a metallic substrate.
 24. A device according to claim 1, wherein the substrate is selected from the group consisting of lacquers, polymers, printing inks, plastics, carton, cardboard, metal such as tin, aluminium, copper, lead, steel.
 25. A device according to claim 1, wherein the Brinell-hardness of the substrate ranges from 10 N/mm²to 1000 N/mm².
 26. A drum for rotative processing of a first layer of a multiple layer substrate, the first layer having a first degree of hardness and the succeeding layers having a second degree of hardness, said drum having: a core with a substantially inflexible outer surface, a flexible force absorbing layer with a third degree of hardness, the flexible force absorbing layer being peripherally attached to the core, and a matrix having the three dimensional structure, the matrix being peripherally attached to the flexible force absorbing layer, wherein the flexible force absorbing layer is selected so that the third degree of hardness is higher than the first degree of hardness and lower than the second degree of hardness.
 27. A method for processing a three dimensional structure into a first layer of a non-planar hard substrate having a planar deviation δ by use of a device having a tool plan and a reaction plan, the tool plan comprising a multiple layer construction, said method comprising the steps of: providing a tool being attached to the surface of a core of the tool plan, providing the core of the tool plan with a flexible force absorbing layer having a thickness τ that exceeds said planar deviation δ disposing a sheet of the substrate between the tool plan and the reaction plan and applying a pressure so as to process the substrate. 